On-site incinerator

ABSTRACT

An on-site incinerator for the burning of refuse without pollution utilizes a first combustion chamber for burning refuse to produce a disposable solid residue and an incompletely combusted gaseous effluent. Gaseous effluent from the first combustion chamber is intimately mixed with air in a mixing zone before its entry into a secondary combustion chamber wherein the combustion of gaseous effluent is completed, and the resulting inert effluent is discharged.

United States Patent Chatterjee et al. May 23, 1972 [54] ON-SITE INCINERATOR 3,563,188 2 1971 Prosser ..1 10/8 [72] Inventors: Anil K. Chatterjee, Tonawanda; James R. 3 gltmann et 10/8 ovc y of a a 0 amCl] -.l [73] Assignee: The Carborundum Company, Niagara P i E m K h w sprague Falls, Attorney-K. W. Brownell [22] Filed: July 31, 1970 [57] ABSTRACT [21] App1.No.: 60,018

An on-site incinerator for the burning of refuse without pollution utilizes a first combustion chamber for burning refuse to (g1 ..110/8 A, 110/8 C, 110/513 produce a disposable solid residue and an incompletely n busted gaseous eflluent. Gaseous effluent from the first com- [58] Field ofSeai-ch ..110/8,8A,8C,18,18C bustion chambcris intimately mixed withairinamixing zone before its entry into a secondary combustion chamber wherein [56} References Cited the combustion of gaseous eflluent is completed, and the UNITED STATES PATENTS resulting inert effluent iS discharged.

3,310,009 3/1967 Jacobs ..1 10/8 6 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION The advantages attendant an on-site incinerator in being capable of immediately destroying refuse thereby minimizing odors and bacterial action, eliminating breeding sites for in sects and rodents, and reducing the frequency for refuse col lection, make its use by factories, hospitals, restaurants, apartment houses, supermarkets and municipalities particularly desirable.

Many conventional on-site incinerators cause air pollution and produce large quantities of organic residue directly in violation of community standards. Low temperature incinerator operation results in the production of smoke, tars, gases and odors consisting of oily vapors. High air velocities in the furnace and chimney stirs up lighted particles and solid particulate which are fire and pollution hazards. Air pollution and the accumulation of unburned residue not only defeats the purpose of an on-site incinerator but drastically reduces the efficiency of the unit.

Other incinerators which reduce some of the aforementioned deficiencies by employing a plurality of burners or heating elements to dehydrate and burn refuse require an uneconomical amount of fuel.

Other incinerators employing gratings, screens, mechanical screws, elevators, valves and mechanical parts in proximity to burning rubbish become clogged and gummed with tar. A decrease in efficiency results and continuous maintenance and replacement of parts is necessary.

The incinerator of the present invention is of the type wherein rubbish is first burned to produce a relatively inert residue of reduced volume and an incompletely combusted gaseous effluent. The effluent gas normally contains ash and stirred up solid particulate, fully combusted gases such as carbon dioxide, and incompletely combusted gases such as carbon monoxide and hydrocarbons. The combustion is regulated by supplying a proportion of the stoichiometric amount of air required for complete combustion. The word air includes gases which will sustain combustion or those containing oxygen.

A secondary combustion chamber is employed to complete the combustion of the combustibles remaining in the effluent gases from the primary combustion chamber. In many on-site incinerators poor design of the secondary combustion chamber causes air pollution. Large combustion volumes and a high percentage of excess air are not the whole answers as witnessed by an open coal or wood fire emitting large volumes of smoke. Neither does the maintenance of a high temperature by the continuous burning of auxiliary fuel in the secondary combustion chamber guarantee complete combustion. Poor mixing of air and gaseous effluent so that the two do not meet before they are cooled below their ignition point results in the emission of unburned gases, hydrocarbon vapors, oily odorbearing vapors and finely divided solids. Heretofore, incinerators of the aforementioned type have not intimately mixed the gaseous effluent from primary combustion with air to form a combustible mixture prior to secondary combustion so as to insure complete combustion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an on-site incinerator which disposes of refuse without pollution by fully diffusing and intimately mixing air and incompletely combusted gaseous effluent prior to secondary combustion thereof.

Other and further objects of the present invention are apparent from the following description.

ln accordance with the present invention, there is provided an incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, a secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, a mixing zone for the passage of gaseous effluent from said primary combustion chamber to said secondary combustion chamber, said mixing zone being provided with means for intimately mixing the gaseous effluent with air, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent.

Also, in accordance with the present invention, there is provided a method for disposing refuses by intimately mixing gaseous effluent and air prior to secondary combustion thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the on-site incinerator of the present invention with a portion cut away.

FIG. 2 is a side elevation view of the incinerator with a portion along a vertical plant through its center axis being cut away.

FIG. 3 is a top view of a portion of the on -site incinerator.

FIG. 4 is a schematic illustration of the control devices associated with the incinerator.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in more detail, FIG. 1 shows the primary combustion chamber 11 as a horizontally aligned cylinder mounted on skid 13 by a plurality of supports 15. It includes a main access door 17 matching an end of combustion chamber 11 so when it is opened, the entire cross sectional area of the primary combustion chamber 11 is exposed for charging.

The main door 17 has a peripheral flange 19 around the periphery of the primary combustion chamber 11. A sealing means of heat resistant material (not shown) is provided therebetween to prevent the escape of gases and fly ash. The main access door 17 is attached to the main combustion chamber 11 by a pair of hinges 21 of heavy duty construction located so as to permit opening thereof in a sideways direction. A fastening means of the screw down type having a bolt 23 is pivotally mounted at one end to the primary combustion chamber 11. The opposite end is threaded and positioned between a forked member 27 located on door 17. A tightening handle 29 screws down on the threaded portion of the bolt 23 so as to firmly close the door 17.

The main access door 17 has mounted thereon with hinges 31,32 a second access door 33 about one-fifth the size of door 17. Clamps (not shown) securely lock but permit periodic opening of the second door 33 to charge additional refuse during operation of the incinerator. A peep hole (not shown) is also provided therein.

The primary combustion chamber 11 includes a plurality of underfire tubes 35, preferably four tubes, embedded in its floor 37. Each tube is axially aligned and extends substantially the entire length of the primary chamber 11. The interior tube ends are closed and the opposite ends extend through end wall 41 to manifold 43. The tubes 35 each have a slit 45 which extends lengthwise and communicates with the interior of combustion chamber 11 through air passage or opening 47 in the floor 37. Although slits are preferable, slots, bore holes or other suitable openings can be utilized.

Overfire air is introduced into the primary combustion chamber through a pair of overfire tubes 48 and 49 located in wall 41. They are axially aligned with one end communicating with corresponding inlets 51 in wall 41 and their opposite ends are connected to air distribution pipe 55. The overfire tubes 48 and 49 are located on opposite sides of outlet opening 5 7 in the top portion of wall 41 so as to oppose the flow of gaseous effluent therethrough thereby aiding in the mixing of air with gaseous effluent and minimizing the carry over of solid ash and particulate. The primary purpose of the overfire tubes 48 and 49 is to direct additional air over the refuse for burning in the primary combustion chamber 11.

The mixing zone or chamber 59 is cylindrically shaped. It presents a passageway connecting the primary combustion chamber 11 at outlet opening 57 to a secondary combustion chamber 61 for the passage of gaseous effluent therethrough. It is axially aligned with and has a cross sectional area approximately one-fifth that of the primary combustion chamber 11. A baffle 63 of resistant material extends transversally of the mixing zone 59 adjacent outlet opening 57 to prevent particulate from being carried therethrough. Although the bafile 63 is shown as extending verticall downward from the top surface of the mixing chamber 59 to block about one-half the cross sectional area thereof. Variations in the position and the area blocked may be employed.

A means for intimately mixing and fully diffusing the gaseous effluent with air is located in the main portion of the mixing zone 59. A pair of air inlets 67, 69 which are preferably tangential to inside surface 71 extend through the wall 73 of the mixing chamber 59. A pair of nonradial air tubes or ducts 75, 77 are positioned in the respective air inlets 67, 69 substantially perpendicular to wall 73. The inside ends of the tubes 75, 77 are shaped to conform to the cylindrical inside surface 71. Two tubes are preferably disposed on opposite sides, or if more than two are used, they are preferably substantially equi-spaced around the inside surface 71. The tubes are complementary so that the air tangentially introduced effects a turbulent circulation or swirling in a given direction.

A secondary combustion chamber 61 is cylindrically shaped. It is axially aligned in the vertical direction perpendicular to the mixing chamber 59 and connected thereto at opening 85. Secondary combustion chamber 61 which has a larger cross sectional area than the mixing chamber 59 effects a change in direction and a decrease in velocity of entering gaseous effluent. A bottom portion 87 which has a conical shape is located below opening 85 so as to create a relatively inactive portion free from turbulence thereby permitting the settling of solid particulate carried over from the primary combustion chamber 11. An access plug 89 can be periodically opened for removing accumulated solid particulate. A support 91 is connected at one end to the bottom portion 87 and at the other to a cross member (not shown) between skids 13.

A burner 97 in the secondary combustion chamber 61 maintains a temperature sufficient to sustain combustion and substantially completely burn the gaseous effluent from the primary combustion chamber. Preferably the temperature therein is maintained so as to exceed about 750 C. A hole 93 opposite opening 85 extends through wall 95 tangential to inside surface 96. A burner 97 positioned therein injects a burning air and gas mixture tangentially into the chamber 61. Preferably one burner 97 of a conventional type having an air supply, fuel supply, ignition and control means combustion employed.

A means for intimately mixing and diffusing gaseous effluent with air is located in the secondary combustion chamber 61 above opening 85. It includes a pair of air inlets 99 and 101 which are preferably positioned tangential to surface 96 so as to complement the burner 97 in effecting a tur bulent swirling of gaseous effluent in a given direction. A pair of tubes 103, 105 which are connected to air distribution pipe 55 are positioned in air inlets 99 and 101. The arrangement and action of tubes 103, 105 is similar to that of tubes 75, 77 in aiding combustion by promoting complete mixing. The inert gaseous effluent is discharged or vented to the atmosphere through a conical or cone shaped stack 107.

The on-site incinerator of the present invention is of steel fabrication. The various inside surfaces that are exposed to high temperatures are covered with a layer of heat resistant material, such as a high temperature resistant castable refractory material. The layer or coating may be conveniently troweled or gunned to the steel shell.

The on-site incinerator of the present invention includes a means for supplying air under pressure to the underfire tubes 35, overfire tubes 48 and 49 mixing chamber tubes 75 and 77, combustion chamber tubes 103 and 105, and the gas burner 97. A single blower having a volute-shaped casing 109 with an impeller therein driven by motor 111 is selected to deliver a sufficient quantity of air at an adequate discharge pressure for maximum conditions. The air therefrom is delivered to duct 113 which has a pipe 115 connected thereto for the passage of air to burner 97. Conduit 117 connects duct 113 to manifold 43 and has a servo valve 119 positioned therein. Manifold 43 is connected to underfire tubes 35 for supplying underfire air. Opening and closing of valve 119 regulates the supply of underfire air. Conduit 121 connects duct 113 with air distribution conduit 55. The air distribution conduit 55 is connected to overfire tubes 48 and 49, mixing tubes 75 and 77 and combustion chamber tubes 103, 105 for air supply. A servo valve 123 in conduit 121 simultaneously regulates the supply of air to all these latter locations.

FIG. 4 schematically illustrates certain control and safety devices for use with the incinerator of the present invention. A control panel 125 which is conveniently mounted on the secondary chamber 61 includes switches 127, 129, 131 and .133 and lights and 137. The power switch 127 is connected to a source of electricity and must be on for the control system to operate. Conventional connections are provided to connect the various control devices to the source of electricity and these connections together with other well-known systems are omitted from the drawing for clarity. The blower switch 129 starts the blower motor 111 and closes valve 119 which regulates underfire air. A timer 139 in the circuit assures that air is supplied to the air distribution conduit 55 for purging the incinerator for about a minute to rid the system of explosive gas. After the purge is completed, light 135flashes indicating that the gas burner 97 may be ignited. Actuation of ignition switch 131 starts the gas burner 97. Thermocouples 141, 143 in the secondary combustion chamber 61 cause the actuation of valve 119 to supply underfire air and the flashing of light 137 when the proper temperature for secondary combustion has been reached. The light 137 indicates that the system is ready for the burning of rubbish. The rubbish in the primary combustion chamber is ignited at this time and the system placed under automatic control by actuation of switch 133. Under automatic control, the thermocouples -147 which are located in the primary combustion chamber 11 and are connected in circuit with the valve 119, automatically cause the underfire air to cut off when dangerously high temperatures are reached. The thermocouples 141, 143 in the secondary combustion chamber 61 are in circuit with the gas burner 97 and valve 119. They operate to maintain proper burning temperatures therein and shut down underfire air when necessary.

In operation, refuse is charged to the primary combustion chamber 11 through the main access door 17. The initial charge should primarily consist of materials that sustain combustion, such as wood, paper, cardboard, and low moisture content materials. The main access door 17 is then closed and the control system purges the incinerator and indicates when the refuse in the primary chamber 11 can be ignited. During operation, less than about 50 percent of the stoichiometric amount of air needed to completely burn the carbon content of the refuse to carbon dioxide is supplied as underfire air. Preferably at least about 30 to 60 percent of this stoichiometric amount of air is supplied to the mixing chamber. Additional air supplied to the secondary combustion chamber 61 not only provides for an excess of air needed for combustion but acts to cool the substantially completely combusted gaseous discharge. The air is evenly metered to the various locations during the entire burning cycle. The temperature in the primary chamber is such that bottles are deformed to lumps and metallic elements are highly oxidized and brittle. These noncombustlbles together with non-combustibles accumulating in the secondary combustion chamber 83 can be periodically removed.

While preferred embodiments of this invention have been described and illustrated, it is to be recognized that modifications and variations thereof may be made without departing from the spirit and scope of this invention as described in the appended claims.

We claim:

1. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, a vertically aligned cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of cornplementary air inlets substantially tangentially a horizontally aligned cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber to said secondary combustion chamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent, said secondary combustion chamber has an opening to said mixing zone and has a floor below the opening.

2. An incinerator according to claim 1 further comprising means for supplying air under pressure to the air inlets of said mixing zone and said secondary combustion chamber.

3. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, a cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of complementary air inlets substantially tangentially directed, a cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber to said secondary combustion chamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent and a baffle disposed in said mixing zone transverse to the flow of gaseous effluent therethrough.

4. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, said primary combustion chamber being cylindrical and horizontally aligned and includes an access door at one end for charging refuse thereto, a cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of complementary air inlets substantially tangentially directed, to a cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber, to said secondary combustion chamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, said primary combustion chamber having a wall at the other end having an outlet to said mixing zone, said wall having a pair of over five openings adjacent said outlet and directed opposite the flow of gaseous effluent, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent.

5. An incinerator according to claim 4 wherein said primary combustion chamber includes a plurality of underfire openings.

6. An incinerator according to claim 5 further comprising means for supplying air under pressure to the overfire openings and underfire openings of said primary combustion chamber and the air inlets of said mixing zone and said secondary combustion chamber. 

1. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, a vertically aligned cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of complementary air inlets substantially tangentially a horizontally aligned cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber to said secondary combustion chamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent, said secondary combustion chamber has an opening to said mixing zone and has a floor below the opening.
 2. An incinerator according to claim 1 further comprising means for supplying air under pressure to the air inlets of said mixing zone and said secondary combustion chamber.
 3. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, a cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of complementary air inlets substantially tangentially directed, a cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber to said secondary combustion chamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent and a baffle disposed in said mixing zone transverse to the flow of gaseous effluent therethrough.
 4. An incinerator comprising a primary combustion chamber for burning refuse to a gaseous effluent and a disposable solid, said primary combustion chamber being cylindrical and horizontally aligned and includes an access door at one end for charging refuse thereto, a cylindrical secondary combustion chamber for burning the gaseous effluent to a substantially completely combusted gaseous effluent, said secondary combustion chamber being provided with a pair of complementary air inlets substantially tangentially directed, to a cylindrical mixing zone for the passage of gaseous effluent from said primary combustion chamber, to said secondary combustion cHamber, said mixing zone being provided with a pair of complementary air inlets substantially tangentially directed for intimately mixing gaseous effluent with air, said primary combustion chamber having a wall at the other end having an outlet to said mixing zone, said wall having a pair of over five openings adjacent said outlet and directed opposite the flow of gaseous effluent, and said secondary combustion chamber having a burner and an outlet opening for discharging completely combusted gaseous effluent.
 5. An incinerator according to claim 4 wherein said primary combustion chamber includes a plurality of underfire openings.
 6. An incinerator according to claim 5 further comprising means for supplying air under pressure to the overfire openings and underfire openings of said primary combustion chamber and the air inlets of said mixing zone and said secondary combustion chamber. 